To a wireless LAN (Local Area Network) in the office or a public wireless LAN has been applied a method in which authorization information such as membership type, expiration date, etc. and configuration information such as WEP (Wired Equivalent Privacy) key, etc. are delivered to a wireless communication terminal of a user as an electronic ticket (computerized or electronic information). With the electronic ticket, the user is allowed to connect his/her wireless communication terminal such as computer, PDA (Personal Digital Assistant), etc. to an access point (also referred to as a public wireless hotspot in the public wireless LAN). Since authorization information and configuration information are distributed as electronic tickets to wireless communication terminals of respective users, the users can dispense with the need for inputting the information to their terminals manually. Consequently, usability or convenience is improved for the users.
According to the method, in general, electronic tickets are distributed through infrared data communication or short-range radio communication.
The user who has received an electronic ticket sets the wireless communication function of his/her wireless communication terminal based on authorization information and configuration information contained in the electronic ticket. Thereby, the user can connect the wireless communication terminal via an access point to a wireless LAN.
When, however, there is a change in the configuration information of a wireless base station as for example in the case where the network topology changes, it is necessary to inform each user who already has access permission (who has already received the electronic ticket) of the change in the configuration information of the base station.
The user needs to reset the wireless communication function of his/her wireless communication terminal based on the configuration information after the change.
As just described, in the conventional wireless LAN, when the network topology has changed, each user is required to download again a new electronic ticket even if the one previously received is still valid and he/she has not lost “access right to the network”.
Besides, a network administrator has to distribute electronic tickets to users who have received it once, which increases network traffic.
In addition, it is inconvenient for users to take some time and trouble to download again a new electronic ticket. Downloading of an electronic ticket drains the battery of a wireless communication terminal and thereby reduces the operable time of the terminal.
As conventional techniques to facilitate the update of a control program for a mobile terminal, for example, Japanese Patent Application laid open Nos. 2000-23209 (Reference 1) and 2004-127187 (Reference 2) disclose “Control Program Management Device and Control Program Updating Method” and “Internet Access System”, respectively.
According to Reference 1, when a mobile terminal connects to a base station, the control program management device checks whether or not the control program of the terminal is in the latest version. If not, the control program management device reads out the latest control program from a control program database and transmits it via the base station to the mobile terminal. Thus, the mobile terminal can update the control program.
According to Reference 2, the Internet access system is provided with first and second wireless LAN access points. The first wireless LAN access point can be accessed from an unspecified number of user terminals, while the second one is accessible only from specific user terminals which have been authenticated based on arbitrary authentication information. A user terminal first connects to the first wireless LAN access point. After an authentication server authenticates the user terminal, the terminal obtains access or configuration information. Based on the access information, the user terminal then connects to the second wireless LAN access point to access the Internet.
The technique described in Reference 1, however, is applicable only to a network in which a mobile terminal can establish communication with a base station even if it has not updated the control program.
In the wireless LAN, when the network topology has changed, a mobile terminal cannot use an access point (wireless base station) that has been available before. That is, the mobile terminal cannot even connect to the wireless base station. Therefore, the technique described in Reference 1 cannot be applied to the wireless LAN Besides, in the Internet access system described in Reference 2, a mobile terminal connects to the first wireless LAN access point to be authenticated by the authentication server every time it accesses the Internet. Consequently, when there is no need for obtaining configuration information through the first wireless LAN access point (when the mobile terminal has already obtained configuration information to connects to the second wireless LAN access point), the mobile terminal performs unnecessary processing. This causes an increase in the processing load of the user terminal as well as an increase in network traffic.
Additionally, in the Internet access system, user authentication is performed with a user ID or a password after the mobile terminal has connected to the second wireless LAN access point. In other words, no authentication is performed during communication through the first wireless LAN access point. As such, communication through the first wireless LAN access point is not protected at all by encryption, and it is undesirable in this situation to transmit/receive configuration information.
As is described above, there has not been proposed a wireless LAN system in which a change in the configuration of a wireless base station is automatically detected to update network configuration only for users who already have an electronic ticket.